Field of the Invention
The present invention relates to an oxy-fuel combustion process integrating the production or generation of oxygen.
Related Art
It is known to extract oxygen from a gas, such as air, by means of ion transport membranes (ITMs), also known as “solid electrolytes”. Said ITMs are capable of ionizing the oxygen molecules present in the air which comes into contact with a first face of the ITM, of selectively transporting the oxygen ions through the ITM and of reconstituting oxygen molecules from said oxygen ions on the face of the membrane opposite the first face (in the direction of movement of the oxygen ions).
It is also known to use oxygen thus produced as oxidant (combustion oxidizer) for the combustion of a fuel and the production of heat.
WO-A-2011/015616 discloses a process for the operation of a glass melting furnace in which the burners are supplied, on the one hand, with fuel and, on the other hand, with hot oxygen resulting directly from an ITM oxygen extractor. According to WO-A-2011/015616, if the contribution of oxygen from the extractor is insufficient, an additional contribution of oxygen is carried out directly to the burner. The flue gases exiting from the melting furnace are passed into a first heat exchanger, referred to as primary exchanger, for the reheating of a heat-exchange fluid, in particular air. The air thus reheated supplies a series of secondary heat exchangers in which compressed air circulates, typically at a pressure of the order of 1.5 to 2×106 Pa. After passing through the secondary exchangers, the compressed air exhibits a temperature of 500° C. to 550° C. This hot compressed air can be further reheated in a boiler in order to reach higher temperatures, for example of the order of 900° C. The hot compressed air thus obtained passes over the ITM extractor for the production of oxygen and the oxygen thus extracted from the hot compressed air is directed directly to a burner. The oxygen-depleted air can be used to activate a turbine for the production of the compressed air introduced into the ITM extractor.
As indicated in WO-A-2011/015616, the properties of hot oxygen, as it exits from the ITM extractor, impose practical limits on the devices in which the hot oxygen circulates. It is thus particularly indicated to use the oxygen immediately after its extraction and thus to locate the ITM extractor close to the burners of the furnace in order to limit the course followed by the oxygen up to the burner, in order to limit the risks of damage to the devices in contact with this oxygen.
The need, for the sake of safety, to locate each extractor close to the associated burner greatly limits the advantage of the process described in WO-A-2011/015616.
This is because the immediate vicinity of a glass melting furnace is generally very restricted in space, in particular at the burners, especially with the devices for supplying the burners with oxidant and the devices for supplying the burners with fuel and, if appropriate, devices for the preheating of the oxidant and/or of the fuel upstream of the burners. Despite this restriction in space, it remains necessary to provide easy access to said burners in order to allow them to be maintained and repaired.
Furthermore, the melting furnaces often comprise a large number of burners. To produce small ITM oxygen extractors, which are unitary for each burner, considerably increases the cost of the installations.
Consequently, the current design of the furnaces generally does not make possible the introduction of ITM oxygen extractors immediately upstream of the burners, as provided in WO-A-2011/015616, whereas, as also explained in WO-A-2011/015616, installation of the ITM extractor at a greater distance from the burner presents a safety problem, generally unacceptable to the operator of the furnace, related to the transportation of oxygen at high temperature.